Empirical Development of Ozone Isopleths: Applications to Los Angeles

Abstract

Understanding quantitative relationships between ambient ozone concentrations and precursor emissions are important to policymakers and stakeholders. Such relationships are often captured as ozone isopleth diagrams developed using air quality models. Model-based approaches have limitations, including errors stemming from uncertainties in inputs and modeled processes, and can be computationally burdensome. We develop and apply an empirical method based on ozone design values calculated in the South Coast Air Basin, California, for 1975-2016 to construct ozone isopleths. The study domain is the area with the highest ozone levels in the US that has experienced high levels of emissions controls. Quadratic and log-quadratic models were constructed, and both capture the actual observations very well (R2 is about 0.98) and recreate the general characteristics of traditional air quality model-generated isopleths. The empirical approach benefits from being based on observations which have high accuracy (but low sp…

Publication
Environmental Science and Technology Letters